Examine source code of Fire History Manager

{
  "description": "A Vue Browser Extension - Firefox History Manager",
  "manifest_version": 2,
  "name": "Fire History Manager",
  "version": "0.1.0",
  "homepage_url": "http://localhost:8080/",
  "default_locale": "en",
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "icons": {
    "16": "icons/history.svg",
    "48": "icons/history.svg",
    "128": "icons/history.svg"
  },
  "browser_action": {
    "default_title": "open History Manager",
    "default_icon": {
      "19": "icons/history.svg",
      "38": "icons/history.svg"
    }
  },
  "permissions": [
    "history",
    "http://localhost/*"
  ],
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "{58b2cebf-6922-4d01-9df6-65dfc1db4056}"
    }
  }
}